Memory arrays for storage, both short-term and long-term, of digital data are well known in the art. Various configurations and implementations of random access memory, known in the art as RAM, provide data storage in relatively small, efficient spaces in comparison to other memory technologies. RAM cells, however, utilize active electronic components, including transistors, to store digital data, resulting in an effectively immediate loss of the stored data in the event of a loss of power to the RAM cells. Hence, RAM memory is referred to as volatile memory.
Non-volatile memory cells, by contrast, maintain stored digital data for some extended period of time without need to maintain power to the memory cell. Such non-volatile memory cells include read-only memory cells, made from various semiconductor devices and known in the art as ROM, and flash memory cells, traditionally made from floating-gate transistors. Such non-volatile memory cells are electrically addressed and thus are faster to access than, for instance, mechanically addressed data storage systems such as magnetic storage (for instance, hard disks) and optical storage (for instance, CD-ROMs). However, non-volatile memory cells have historically contrasted unfavorably with volatile memory and mechanically addressed data storage in terms of cost, efficiency and utility. While both volatile and mechanically addressed storage is relatively cheap, densely packed and freely writeable and rewriteable, non-volatile memory has historically been expensive, large and with limitations on how many times the cell may be written to, as with a flash memory cell, or not subject to being rewritten at all, as with ROM memory cells.
On that basis, non-volatile, electronically addressed memory cells have historically been used sparingly in contrast with volatile memory and mechanically addressed non-volatile data storage. However, recent process improvements in non-volatile memory have made the use of non-volatile memory more viable. In particular, flash memory applications have become increasingly common, while new non-volatile memory techniques are in development.
The proliferation of flash memory has, however, created new challenges. In particular, while contemporary flash memory relatively reliable in comparison with historic flash memory, contemporary flash memory remains relatively unreliable in contrast with many other forms of memory, both volatile and non-volatile. While the relative unreliability of flash memory may be acceptable in consumer electronics, for instance, in life-critical applications, such as in medical devices, data unreliability may create challenges in using and implementing flash memory arrays.